



i atented July 30, 1935 FFic' ihlans Werner Fiedler, Leipzig, Germany No Drawing Application May 18, 1931, Serial No. 533,269. lln Germany May 21, 1930 1 Claim.

My invention relates to depilatories and to the method of applying same.

It is an object of my invention to prevent irri tation or other undesirable action of the depilatory on the skin. To this end I protect the skin by a layer of a substance which is not attacked by the clepilator and apply the depilator on top of such protective layer.

Many depilatories have already been suggested, most of them being designed as substitutes for shaving. However all these depilatories are known to irritate the skin. This is due to the fact that the chemical constitution of the hair and of the upper layers of the skin are substan tially equal, consisting both of keratins and be-= ing coated superficially with an extremely thin layer of fat. If keratolytic reagents act on this layer it is saponified by the strong alkali present in all depilatories and the keratins of the skin and the hair are destroyed at the same time the skin being attacked and irritated.

In the compounding of the depilatories hitherto suggested the substantially equal chemical constitution of the hair and the upper layer of the skin has not been taken into consideration. The composition of depilatories is either determined with a view to presenting the active substances in a pleasant form, for instance, by adding froth-generating agents, zinc oxide, sugar, kieselguhr, flour and the like, or with a view to neutralizing the free alkali which is formed by the hydrolytic dissociation of the normally present sulfides. However, it has been found to be absolutely impracticable to destroy the keratin of the hair while leaving unaltered the keratin of the skin.

According to the present invention the keratin of the skin is protected against keratolytic action by rendering the epiderm proof against the ac tion of the depilatory before applying the latter.

Suitable substances caused to be absorbed by the skin form a protective layer on and in the superficial epithelium layer. In view of the fact that the saponification of the thin layer of fat on the skin proceeds rapidly, protective substances, such as albumin, gelatin, starch, fat, oil,

mineral substances, cellulose and the like, were as oils and fats, covering the skin, will combinewith the depilatories, whereby the dissociation of the keratolytic reagents is considerably suppressed and their action greatly diminished.

I have now found that the protective substances referred to become particularly active if applied in a suitably dispersed, preferably emulsified, condition in which they are not absorbed by the depilator but are precipitated or fiocculated in finest subdivision. This action is due to the fact that the protective substance is a colloid, while the depilatory is present in ionized condition. The protective colloidal substance is absorbed thoroughly by the porous upper layer of the skin,-

and forms an insulating layer which cannot be removed by the depilatory so that the skin is protected against the detrimental influence exerted by the depilatory.

My invention therefore comprises treating the skin before shaving with anemulsified substance which enters the skin and protects the skin against the action of the depilatory, while that part of the emulsion, which is not absorbed by the skin, in coming in contact with the ionized depilatory, is fiocculated or precipitated and thus allows the depilatory .to remove the hairs.

Preferably the protective substance and the depilatory are enclosed ready for use in separate vessels surrounded by a suitable envelope.

Colloids of the most various kinds which can be emulsified, may be employed as protective substances.

A. protective emulsion may for instance be prepared in' the following manner.

10 parts finely ground mechanical wood pulp, are suspended in 300 parts water to which 36 parts caustic soda solution (specific weight 1.091) are added. The liquid is heated under pressure to about 200 C. for several hours and continuously agitated until a complete solution has been obtained. This solution has a slightly brownish color and opalescent turbidity and is therefore filtered with charcoal or some other decolorizing agent. The clear and colorless filtrate is dialyzed until the alkaline reaction disappears, it is then thickened to the consistence of syrup and changed into an emulsion by means of an emulsifying .agent, such as Turkey-red oil or a mixture of the oil with other substances. This emulsion is first spread on the skin, whereupon any suitable depilatory may be applied in a well known manner without the skin being in any way affected by it.

Various changes may be made in the details disclosed in the foregoing specification without departing from the invention or sacrificing the 

